Secondary air injection systems have been used with various types of automotive engines for many years. Such systems typically involve the use of an engine driven pump to deliver air through a suitable conduit system to the exhaust manifold or other parts of the exhaust system of the engine. The excess air provides additional oxygen which reacts with unburned constituents in the engine exhaust.
Design of air injection systems is complicated because flow through the systems is intermittent and condensation and resulting corrosion may develop within the systems due to the fact that the various components are not continuously purged by air passing therethrough. The present valve and mounting system are characterized by structures which are uniquely adapted to avoid corrosion problems which have rendered prior art valve and mounting systems inadequate. The air injection valve and mounting system according to the present invention uses plastically formed threads which are placed in a full-section thickness of the air injection valve body and which are engaged with similar full thickness threads formed in a receiving socket which comprises a portion of an air discharge manifold.
Press-formed threads have been used for interlocking pipes, as shown in U.S. Pat. No. 1,365,884 to Bayne, U.S. Pat. No. 2,476,656 to Galbraith, U.S. Pat. No. 3,308,908 to Bunn, U.S. Pat. No. 4,728,127 to Westberg and U.S. Pat. No. 4,773,679 to Hangebrauck. However, such interlocking structures have not been used for the purpose of mounting valve assemblies in the corrosive atmosphere of automotive engine exhaust gas.
It is an object of the present invention to provide an automotive air injection valve and mounting system which offers superior resistance to corrosion.
It is yet another object of the present invention to provide an air injection valve and mounting system which is lighter in weight than conventional systems.
It is yet another object of the present invention to provide an air injection and mounting system having fewer parts than conventional systems.
Other objects, features and advantages of the present invention will become apparent to the reader of the specification.